What is the Scientific Assessment of Meal Replacement Strategies for Weight Loss? The use of these pre-measured lower calorie products to facilitate a RCD has been shown to be most effective for weight loss (Levitsky and Pacanowski, 2011). In a meta-analysis done by Heymsfield et al. (2003) on meal replacements, the researchers examined six studies that met strict research methodology criteria. The authors concluded that partial meal replacement programs can be safely and effectively utilized, and are shown to improve weight-related risk factors of disease in addition to subjects losing about 7-8% of initial weight over the course of a year.

Will you be Hungrier on Meal Replacements? It has been submitted that individuals who consume fewer calories during one meal replacement may compensate for the calorie deficit at the subsequent meal (Levitsky and Pacanowski, 2011). This does not appear to be the case. Although a true mechanism is unknown at this time, Levitsky and Pacanowski propose that people may adapt to the meal replacement as the 'norm' for the meal. Thus individuals may make behavioral modifications that reduce the need to consume more food. Also, the visualization of a smaller portion controlled meal may help individuals slow down while eating and pay more attention to internal cues of satiety. Future studies are warranted to determine any physiological mechanisms associated with meal replacement plans and appetite.

Are Meal Replacements Safe for Individuals with type 2 Diabetes?The Look AHEAD trial (Pi-Sunyer et al., 2007) is an ongoing study of 5,145 overweight subjects with type 2 diabetes undergoing a lifestyle intervention for weight loss that includes 175 minutes/week of moderate intensity physical activity along with meal replacements (liquid meal replacements and frozen food entrees) combined with conventional foods. One-year results show the subjects have lost an average of 8.6% of initial body weight. Cardiovascular fitness has improved by 21% during the 12 months. In addition, subjects have shown a significant improvement in some biomarkers associated with metabolic syndrome.

Applications for the Exercise ProfessionalExercise professionals are very aware that successful weight loss programs are multi-factorial approaches that include regular exercise, behavior modification, healthy nutrition education, portion control, and S.M.A.R.T. goal setting for clients. Meal replacements are proving to be a successful option for creating dietary caloric deficits. However, for prolonged weight regain prevention the exercise professional's role is truly paramount in motivating clients to maintain their reduced body weight.

Side Bar 2: Three Common Questions About Meal Replacements1) Should anyone start a reduced calorie diet with meal replacements? No, before starting a reduced calorie diet it may be beneficial for the client to consult her/his doctor about the weight loss plan, especially if there is a pre-existing health condition. In addition, medications may need to be adjusted, especially for those persons interested in replacing two or more meals per day.
2) How long should a person use meal replacements? If utilizing one meal replacement per day a person can continue indefinitely, as long as he/she monitors intake at other meals to maintain a well-balanced diet. If the plan is to utilize two or more meal replacements per day it is recommended that the client seek the advise of a clinical weight loss specialist.
3) Are there options to consume ONLY meal replacements to gain greater and faster weight losses? Yes, these types of meal replacements are called full formula meal replacements and are the most aggressive when a person has a large amount of weight to lose. These are medical grade products that are formulated specifically to provide all recommended macro- and micronutrients during this RCD. These products are only available from a physician or weight loss center that specializes in medical weight loss.

Bios:Michelle G Kulovitz, MS is a doctoral candidate in Exercise Science at the University of New Mexico, Albuquerque. She currently holds a MS in Nutrition as well as a MS in Exercise Science. Her research
interests are in weight management and weight loss maintenance.

Len Kravitz, PhD, is the program coordinator of exercise science and a researcher at the University of New Mexico, where he won the Outstanding Teacher of the Year award. He has received the prestigious Can-Fit-Pro Lifetime Achievement Award and was chosen as the American Council on Exercise 2006 Fitness Educator of the Year.